The sugar to which all other sugars are converted during human metabolism is:
- A. sucrose
- B. fructose
- C. glucose
- D. maltose
Correct Answer: C
Rationale: Glucose is the primary sugar used by the body for energy and is converted from other sugars during metabolism. Sucrose is a disaccharide composed of glucose and fructose, not the end product of sugar metabolism. Fructose is a simple sugar found in fruits but needs to be converted to glucose for cellular energy. Maltose is a disaccharide composed of two glucose units and is not the final product of sugar metabolism in humans.
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Which of the following types of fiber is not a carbohydrate?
- A. gums
- B. lignin
- C. pectin
- D. cellulose
Correct Answer: B
Rationale: Lignin is the correct answer because it is a type of fiber that is not a carbohydrate and provides structure to plant cell walls. Gums (choice A), pectin (choice C), and cellulose (choice D) are all types of dietary fiber that are carbohydrates. Gums are a type of soluble fiber, pectin is found in fruits and is a soluble fiber, and cellulose is a type of insoluble fiber found in plant cell walls.
Which monosaccharide only occurs naturally in foods in combination with another sugar as a disaccharide?
- A. Fructose.
- B. Galactose.
- C. Sucrose.
- D. Maltose.
Correct Answer: B
Rationale: The correct answer is B, galactose. Galactose naturally occurs in foods only when it is combined with glucose to form lactose, a disaccharide found in milk. Fructose is a monosaccharide found in fruits and honey. Sucrose is a disaccharide composed of glucose and fructose, commonly known as table sugar. Maltose is a disaccharide formed by the combination of two glucose molecules.
What is the primary function of protein in the diet?
- A. supply energy.
- B. synthesize vitamins.
- C. build and repair tissue.
- D. store glycogen.
Correct Answer: C
Rationale: The primary function of protein in the diet is to build and repair tissues. Proteins are essential for the growth, maintenance, and repair of body tissues like muscles, skin, and organs. While proteins can be a source of energy, their primary role is not to supply energy, making choice A incorrect. Choice B is also incorrect as proteins do not synthesize vitamins; rather, they are essential nutrients themselves. Choice D is inaccurate because glycogen is a form of stored glucose in the body, not a function of protein.
How many kilocalories (kcal) are provided by 35 g of fat?
- A. 140
- B. 245
- C. 315
- D. 360
Correct Answer: C
Rationale: Fat provides 9 kcal per gram, so 35 grams of fat provides 315 kcal. Therefore, the correct answer is C. Choice A (140) is incorrect because it doesn't consider the energy content of fat. Choice B (245) is incorrect as it miscalculates the kilocalories provided by 35g of fat. Choice D (360) is incorrect because it overestimates the kilocalories provided by 35g of fat.
Which enzyme is produced by the parotid gland?
- A. Salivary amylase
- B. Sucrase
- C. Maltase
- D. Lactase
Correct Answer: A
Rationale: The correct answer is A, Salivary amylase. Salivary amylase is an enzyme produced by the parotid gland that initiates starch digestion in the mouth. It helps break down starch into maltose, a simpler sugar. Choices B, C, and D are incorrect because sucrase, maltase, and lactase are enzymes involved in the digestion of disaccharides like sucrose, maltose, and lactose, respectively, in the small intestine, not in the saliva.